s390/dasd: protect device queue against concurrent access

Vulnerability Description

In the Linux kernel, the following vulnerability has been resolved: s390/dasd: protect device queue against concurrent access In dasd_profile_start() the amount of requests on the device queue are counted. The access to the device queue is unprotected against concurrent access. With a lot of parallel I/O, especially with alias devices enabled, the device queue can change while dasd_profile_start() is accessing the queue. In the worst case this leads to a kernel panic due to incorrect pointer accesses. Fix this by taking the device lock before accessing the queue and counting the requests. Additionally the check for a valid profile data pointer can be done earlier to avoid unnecessary locking in a hot path.

References

• https://git.kernel.org/stable/c/ebdc569a07a3e8dbe66b4184922ad6f88ac0b96f
• https://git.kernel.org/stable/c/f75617cc8df4155374132f0b500b0b3ebb967458
• https://git.kernel.org/stable/c/f1ac7789406e2ca9ac51c41ad2daa597f47bdd4d
• https://git.kernel.org/stable/c/c841de6247e94e07566d57163d3c0d8b29278f7a
• https://git.kernel.org/stable/c/6062c527d0403cef27c54b91ac8390c3a497b250
• https://git.kernel.org/stable/c/dc96fde8fcb2b896fd6c64802a7f4ece2e69b0be
• https://git.kernel.org/stable/c/9372aab5d0ff621ea203c8c603e7e5f75e888240
• https://git.kernel.org/stable/c/db46cd1e0426f52999d50fa72cfa97fa39952885